1. Field of the Invention
The present invention relates the production of styrene, and particularly to a zeolite catalyst for the alkylation of toluene with methanol to selectively produce styrene and ethylbenzene.
2. Description of the Related Art
Styrene is a commercially valuable commodity typically produced using benzene and ethylene feeds in a two-step process. The first step is the alkylation of the benzene with ethylene to produce ethylbenzene. In the second step, ethylbenzene is dehydrogenated to form styrene. This reaction occurs at high temperatures (greater than 600° C.) using an iron oxide catalyst. The reaction is highly endothermic and thermodynamically limited.
The production of styrene from ethylbenzene consumes ten times more energy than the production of most other chemicals, and is also a major contributor to the production of harmful greenhouse gases, such as methane gas emissions. The current global production capacity of styrene is near 26 million tons per year and is increasing at a steady rate (˜3.7% per year). Styrene is used as an intermediate chemical in the production of various polymers, mainly polystyrene.
There is a need for an alternative technique for the producing styrene that is relatively energy efficient and that reduces greenhouse gas emissions. Thus, a zeolite catalyst for the alkylation of toluene with methanol solving the aforementioned problems is desired.